Bug 1256027 - Coerce VS2015 into compiling without warnings; r=froydnj

End state is Waldo's original patch, which so far has been the only
version that compiles on VS2015.

MozReview-Commit-ID: FCOaEvMqYB4

--HG--
extra : source : 8d59e338a5bd76338f0fe28ff589726bc4438fdd

toolkit/xre/nsNativeAppSupportWin.cpp

@@ -506,7 +506,7 @@ struct MessageWindow {
             ::_snwprintf(classNameBuffer,
                          128,   // size of classNameBuffer in PRUnichars
                          L"%s%s",
-                         wwc(NS_ConvertUTF8toUTF16(gAppData->remotingName).get()),
+                         static_cast<const wchar_t*>(NS_ConvertUTF8toUTF16(gAppData->remotingName).get()),
                          L"MessageWindow" );
             mClassName = classNameBuffer;
         }
@@ -669,7 +669,7 @@ nsNativeAppSupportWin::Start( bool *aResult ) {
     ::_snwprintf(reinterpret_cast<wchar_t*>(mMutexName),
                  sizeof mMutexName / sizeof(char16_t), L"%s%s%s",
                  MOZ_MUTEX_NAMESPACE,
-                 wwc(NS_ConvertUTF8toUTF16(gAppData->name).get()),
+                 static_cast<const wchar_t*>(NS_ConvertUTF8toUTF16(gAppData->name).get()),
                  MOZ_STARTUP_MUTEX_NAME );
     Win32Mutex startupLock = Win32Mutex( mMutexName );